1. Field of the Invention
This invention relates to methods for transferring a uniform phosphor layer on an object, and, more particularly, to a method for transferring a uniform phosphor layer that converts the wavelength of light emitted by an LED, and a light-emitting structure fabricated thereby.
2. Description of Related Art
Phosphor materials are widely applied to LED packages that include blue pump LEDs and green or red phosphors and emit white light (e.g., a mixture of blue light emitted from the blue pump LEDs with green or red light converted from the blue light by the phosphor materials). Conventional methods for depositing phosphor materials on blue LED chip or package assembly include:
Slurry method: phosphor powders are distributed insilicon, epoxy resin or solvent filling material, to form a phosphor mixture, and the phosphor mixture is applied to a surface of an LED or a package lens material by spraying coating or immersing coating techniques.
The above conventional method faces a problem that an LED has an uneven package surface. The slurry method forms a layer of particles that does not have a uniform thickness. As a result, the LED does not have uniform light color points and the light converted by the phosphors has poor color uniformity. Moreover, the conventional methods are difficult to be applied to an uneven surface and to form a uniform layer of phosphors. It is a real challenge to use the conventional methods to satisfy lighting application demands.
The conventional method still suffers the problems that the distribution capacity of phosphors cannot be controlled, the LED does not have consistent light color points, and the light converted from the phosphors has poor color uniformity. Therefore, how to provide a method for transferring a uniform phosphor layer on an article and a light-emitting structure thus fabricated is becoming one of the most popular issues in the art.